Add unit tests, Playwright e2e tests, and CI workflow

[Copilot]

Adds vitest-based unit test infrastructure and Playwright end-to-end tests, with a GitHub Actions workflow to run both automatically.

Unit test coverage (42 tests)

• src/lib/utils.ts — isValidUrl, formatMinutes, calculateMarketPrice, getProjectLinkType (all editor type detection paths including onshape, fusion, blender, freecad, solvespace)
• src/lib/currency.ts — minutesToClay, minutesToBricks, calculateShopScore, calculateMinutes, calculateCurrencyPayout, calculatePayouts (pre/post beta cutoff, base printer logic, multipliers)

Playwright e2e tests (8 tests)

• e2e/home.test.ts — homepage heading/content, login button, FAQ section, footer
• e2e/approved-editors.test.ts — page heading, all editors listed, back link, no TinkerCAD notice

CI

• .github/workflows/test.yml — separate unit and e2e jobs (e2e depends on unit passing), Node 22, explicit contents: read permissions, Playwright report uploaded as artifact

Scripts

• npm test — run vitest unit tests
• npm run test:e2e — run Playwright e2e tests
• npm run test:all — run both vitest and Playwright

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[ArcaEge]

@copilot use playwright instead and/or alongside

[Copilot]

@copilot use playwright instead and/or alongside

Added Playwright alongside vitest in b35b0e1. The setup includes:

• @playwright/test as a dev dependency
• playwright.config.ts — builds + previews the app, runs tests from e2e/
• e2e/home.test.ts — 4 tests for homepage content, login button, FAQ, footer
• e2e/approved-editors.test.ts — 4 tests for the approved editors page
• Scripts: test:e2e (playwright only), test:all (vitest + playwright)
• CI workflow updated with separate unit and e2e jobs (e2e depends on unit passing first, uploads Playwright report as artifact)